Blasting machine



' March 21, 1944e ,1 E, FOSTER BLASTAING MACHINE Filed April 25, 1942 3 Sheets-Sheet 1I.

" INVENTOR. J4/fas E? F0 7327? March 21, 1944.

J. E. FOSTER BLAST'ING MACHINE Filed April 25, 1942 F/G. Z.

3 Sheets-Sheet 2 INVENTOR.

Jc/L/ Us 5. F27 STE/Q' March 21 1944. J. E. FOSTER BLSTING MACHINE med April 25,-1942 3 Sheets-Sheet 5 IN VENTOR. s refe dat* /4 7' 7 {Ji/Vfyf Patented Mar. 2l, 1944 UNITED STATES PATENT OFFICE BLASTING MACHINE Julius E. Foster, Washington, D. C.

Application April 25, 1942, Serial No. 440,525

('Granted under the act of March 3, 1883, as

amended April 30, 1928; 370 0. G. 757) 9 Claims.

The invention described herein may be manufactured and used by or for Government for governmental purposes, without the payment to me of any royalty thereon.

My invention relates to blasting machines, particularly intended for projecting an abradant material, such as shot, or grits, or the like, in a pre-determined direction.

One object of my invention is to provide a blasting machine of the centrifugal type, in Which an abradant material is supplied to the machine and is then centrifugally projected by and from the machine in a definite pre-determined direction.

Another object of myinvention is to provide a blasting machine of the centrifugal type, in which the directional control may be easily and readily established by controlling the point of feed of the abradant material to a projecting or throwing part of the machine, such as a radial slinger blade.

Another object of my invention is to provide a blasting machine of the foregoing type, in which an operating element of the machine is protected against wear and attrition from impinging abradant particles, by disposing a loose protective layer of the abradant particles over the surface of that element, so the loose particles will receive the impact force of a continuing supply stream of the abradant particles that is to be edto a throwing part of the machine.

Another object of my invention is to provide ablasting machine in which the abradant material is fed to the inner end of a projecting or throwing part of the machine, such as a radial slinger blade, solely by centrifugal for-ce and without the use of mechanical devices, such as impel'lers.

Another object of my invention is to provide a blasting machine in which the abradant material flows freely, without mechanical pushing, through its feed path to the ultimate slinger part of the machine.

Another object of my invention is to provide a blasting machine in which the abradant material is centrifuged and directionally controlled to the feed end of the slinger part of the machine from which the material is discharged at a high blasting velocity.

The blasting machine that is constructed in accordance with the principles of my invention, consists of a rotatable head or rotor. shaped like a wheel, and provided with several radially disposed slinger blades. The outer ends of the slinger blades are open and the blades are held in xed position on a rotor disc or spider, with a central space between the inner ends of the blades. The abradant material is supplied in quantities, or in a continuous stream to a distributor at the central axial zone of the rotor, and, from there, a small quantity of the abradant material is fed to the inner end of each slinger blade when the blade reaches a pre-determined position in its path of travel, so the abradant material will be projected and discharged from the outer end of the blade when the blade has moved through a pre-determined angle, beyond the position at which the abradant material was supplied to the blade. Y

The abradant distributor, which feeds or supplies the abradant material to the inner ends of the slinger blades, comprises, briefly, a concentric cylinder .at the inner ends of the blades, and it is secured to the rotor in fixed concentric position, to rotate in fixed position with respect to the blades. The cylinder is provided with transfer passages through the cylinder wall, the pas.- sages being respectively positioned relative to the several slinger blades to transfer the abradant material to their respective associated blades.

A gondola or basket is pivotally mounted, on the outside of the cylinder, yadjacent to each transfer passage, to receive the Supply of abradant. that is to be fed to the associated slinger blade. When each bladereaches a pre-determined position in its path of travel, as previously blade.

The abradant in the cylinder is supplied to each basket or gondola through a short stubby conduit having its inner end fixed in the transfer passage in the cylinder wall. The outer end of the conduit extends down ,into the space in the basket, to a level below the top edge plane of the basket. 'I'he abradant passes from the cylinder to each basket, through the conduit,

. until the level of the abradant reaches up to the end of the conduit and shunts off further transfer of the abradant from the cylinder into the basket.

The abradant in the basket thus co-operates with the conduit to serve as its own valve to control further free flow of the abradant into the basket from the cylinder. After some of the abradant is fed from the basket to the associated blade, and the level of the abradant is lowered in the basket, more of the abradant is permitted to pass into the basket, until` the conduit is again shut off by the new raised level.

After each basket is momentarily tipped, at the desired position, to permit a small quantity of the abradant material to be thrown onto the slinger blade, the tipping mechanism is released to permit the basket or gondola to resume its normal original position, whereupon the basket receives an additional quantity of the abradant material from the supply cylinder of the distributing mechanism.

The construction and operation of the machine are shown in the accompanying drawings, in y which Figure 1 is a side elevational view, partially in section, of the blasting machine;

Figure 2 is an enlarged sectional view including the feed cylinder and the control magnet;

Figure 3 is an end view into the feed cylinder, with parts in section and parts broken away;

Figure 4 is a schematic plan view showing a feed basket and its slinger blade;

Figure 5 is an end elevational view of the fork and bell-crank on a basket shaft;

Figure 6 is an elevational View of a bracket for the bearing of the basket shaft; and

Figures '7, 8 and 9 are, respectively, end, plan and side views in elevation, with parts in section and parts broken away.

As shown in 'FigureV 1 of the drawings, a blasting machine IIJ, constructed in accordance with the principles of my invention, is shown as comprising, briefly, a rotatable head or rotor II mounted at one end of a drive shaft I2, that is supported for rotation between two supporting bearings I3 and I4. The drive shaft is provided with a suitable Vdriving pulley I5, by means of which the shaft may be driven, from any suitable source of motive power, to rotate the shaft and the rotor at high speed.

, The rotatable head or rotor comprises, briefly, a spider or'back disc plate IB provided with a hub Il which is keyed to the drive shaft I2 by a key I8. The disc I5 carries several slinger blades 20, that are radially disposed on, and fixedly secured to, the disc I5, by anchoring plates 2| that are bolted to the disc I6, and that hold the slinger blades 2U in place by fitting over tapered edge .anges 22, at the edges of the blades 20, that rest against the disc I6. The anchoring plates 2|, are anchored to the disc I6 by suitable anchoring means, such as bolts 23, and are provided with inclined or tapered edge surfaces, outwardly divergent, to co-operate with backing anchor plates 24, to hold the slinger blades against moving in response to centrifugal force. The co'-operating edge of the slinger blade flange is convergingly tapered, so the slinger blade is held as a wedge by co-operating anchor plates' on opposite sides of the slinger blade.

The drive shaft I2 is driven at a relatively h'igh speed, to rotate the disc I6 and the slinger blades at the same high angular velocity, in order to impart a high blasting velocity to the abradant material, by the time that abradant is moved out to the ends of the respective slinger blades, and projected and discharged by and from the blades in a pre-determined direction, against an object that is tobe blasted.

The accelerating vsurface 25 of each slinger 75 blade 20 is relatively smooth and continuous, so the abradant material can move freely along the full length of the slinger blade, without interference of any kind that would diminish the momentum of the accelerated abradant material and absorb some of the kinetic energy of the abradant. The free uninterrupted passage of the abradant material along the inner surface of the slinger blade tends to maintain a uniformity of travelling time of the abradant material on each one of the blades. The discharge point will therefore be uniform and constant on the several blades, when the several blades are fed with the abradant material at the same point on the orbital path traversed by the inner ends of the blades.

The abradant material is supplied to a main distributor 30, from which it is fed to the inner ends of the blades 20. As shown in the drawings, the distributor comprises a supply cylinder 3|, co-axially secured to the end of the drive shaft I2, and concentrically disposed within a central opening of the rotor, at the inner ends of the blades, to be rotated with the rotor.

The distributor cylinder 3| is provided with four openings or transfer passages 32, 33, 34, and 35, through its wall. The transfer passages 32, 33, 34 and 35 are equally spaced around the periphery of the cylinder, each passage being located generally to be slightly in advance of the inner end of an associated slinger blade 2D. A short conduit 36 is securely disposed in and extends through and beyond each of the transfer passages. The inner end of each conduit 36 is disposed flush with the inner surface of the cylinder 3|, to permit free movement of the abradantfrom the cylinderinto the conduit. The outer end of the conduit 36, however, projects a short distan-ce beyond the outer surface of the cylinder 3| to direct the abradant material into a cooperating basket or gondola 38.

Since the distributor cylinder 3| is xedly connected to the drive shaft I2, to rotate as a unit with the shaft I2 and with the rotor I I, the abradant material that is supplied to the inside of the cylinder 3| will be centrifugally distributed around the inner surface of the cylinder 3|; and the abradant material adjacent the transfer passages or openings 32, etc., will be thrown outward, through those passages and the associated conduits 36, into the associated baskets 38.

In order to receive the `abradant material that is thrown outwards through the conduits 36, the gondolas or baskets 38 are supported on the cylinder 3|, directly outside of and adjacent to the ends of the transfer conduits 36. Each basket 38 is pivotally supported on a pivot shaft 39 disposed between two bearings 4c and III in two side brackets 42 and 43 that are securely mounted on the cylinder 3| by Vwelding or bolts.

Since the pivot shaft 39 is on an axis below and beyond the normal center of gravity 45 of the basket 38, the basket 33 is unstable unless` otherwise supported.

Each basket 38 is supported on its shaft 39 by strap brackets 44 welded to the sides of the basket 38.

Further, the basket 38 is supported on the pivot shaft 39, slightly off center, so the center of. gravity d5 will be in advance of the radius line through the pivotal axis of the basket. With such unstable support, the basket would normally tip counter-clockwise about the pivotal axis.

In order to hold the basket against casual' angular tipping movement, however, until a tip- The operating arm 49 and the plate 62 are disposed for remote actuation by an electro-magnet 5| that is located adjacent the outer edge of the distributor cylinder 3|, as shown in Figures l and 2.

The tilting mechanism 46 imparts a small anguiar movement to the basket `38, as shown in Figure 3, from the solid line position to the broken line position, when some abradant is to be fed onto the slinger blade 20.

Such angular movement is imparted to the basket 38 by the tilting mechanism acting upon a fork 52 that is keyed to the pivot shaft 39. The fork 52 is shown as consisting of two sections tted over the pivot shaft 39 and bolted together to constitute the fork. The fork is operated `by the bellcrank embodying the arms 41 and 49. A roller 54 on the end of the arm 41 fits into the fork and controls the movementJ of the fork according to the position of the bellcrank. The bell-crank is pivotally supported, for its angular movement, between two spaced side walls 55 and 56 of a bracket 51 that is secured to the distributor cylinder 3|.

When the tipping operation is to take place, the bell-crank 53 is operated by the magnetic attraction and retardation of the operating arm 49 by the electromagnet 5| acting on an armature plate 62 that is supported at the end of the operating arm 49 of the bell-crank.

Disregarding friction for the moment, the fork 52 and the bell-crank arm 49 will be biased towards their outermost positions :by the centrifugal force developed during rotation of the rotor and the distributor cylinder. In order to limit the outward movement of the fork 52 and of the bell-crank arm 49, the stop lug 48 extends from the side walls of the bearing bracket 51, for the bell-crank pivot shaft, to serve as a stop, to define the outer limit position of the bellcrank arm 49 when the bell-crank is moved away from the distributor cylinder 3| in response to centrifugal force. In that outer position of the bell-crank, the control arm 49 of the bell-crank may be made to be lagging slightly behind the radius line from the center axis of the distributor cylinder 3| through the pivotal axis of the bell-crank.

The outer end of the bell-crank arm 49 carries the magnetizable plate 62 that is toserve as an armature to be attracted by the adjacent control electro-magnet 5|. 'I'he armature plate 62 is symmetrically supported on the bell-crank arm 49y and the center of gravity on the bell arm 49 and the plate 62 is therefore also behind the radius line from the center of the rotor distributor axis through the pivot axis of the bell-crank. Consequently, during (rotation of the rotor, centrifugal force further tends to turn the bell-crank to move the bell-crank arm 49 to its outermost position, and thereby move the basket 38 to its loading position.

The control electro-magnet 5| is shown as comprising a magnetic core structure 64 of substantially U-shape with an energizing coil 654 The core structure 64 has two pole faces 61 and 68, that are separated by an air gap 69. The two pole faces 61 and 68 are partially recessed to embody inwardly facing shoulders 1| and 12 that are to be directly underneath the armature plate 62 at the end of the bell-crank during rotation of the rotor. The air gap space between the lower or outer surface of the armature plate 62 and the shoulder surfaces 1| and l2 of the electro-magnet may thus be made relatively small.

lThe two faces also embody the outer side Walls 15v and 16 at the outer edges of the shoulders 1| and 12. The space between the inner wall surfaces of the side walls 15 and 16 is slightly larger than the corresponding dimensions of the armature plate 62 when the armature plate is moved through that space at the end of the bell-crank, during rotation.

By means of the shoulder and side wall arrangement, a magnetic attractive force is impressed upon the armature plate 62 irrespective of its position during the turning movement on its pivotally supported bell-crank.

In order to permit suflicient clearance between the armature plate 62, at the end of the bellcrank, and the shoulder surfaces 1| and 12, the electromagnet is spaced a suilicient distance away from the main axis of rotation of the rotor to be free of the armature plate 62 when the armature plate is in its furthermost radially extended position.

The angle through which the bell-crank must be moved, by theretarding magnetic friction force of the electro-magnet on the armature plate 62. depends upon the angle through which the basket. 3B must be turned, to shift from `normal loading position toits unloading position, at which the abradant particles are fed, in a trailing slip stream onto the adjacent surface of the slinger blade. -l As shown in the drawings, when the basket 38 is in the normal loading position, the rear or lagging surface of the basket is inclined slightly upwardly from a plane through the pivot shaft 39, and parallel to a tangent to the cylinder 3|. In order to permit the abradant materials or particles to fall free from the basket 38 onto the slinger blade, when the basket is moved to unloading position, the basket should be moved through a sufficient angle to bring the inner surface 38d of the rear wall of the basket to an angle below the tangent parallel, as shown in Figure 3.

That angle constitutes the operating angle of the basket,. and determines the angle through which the fork must be moved by the bell crank to establish a desired operation of the basket to feed abradant to its slinger blade.

Since turning movement of the fork will tend to turn the upper fork arm towards the cylinder surface, which would limit the fork movement, the

initial or normal position of the fork during the loading operation of the basket will be somewhat under-inclined from the horizontal line to the axis 1 of pivot shaft 39, when the line between the axis of pivot shaft 39 and the rotor axis is considered vertical. The distance between the axis of the pivot shaft 39 and the pivotal axis of the bellcrank must be sufficiently great, with respect to the overall length of the bell-crank arm 41, to

permit and to assure free movement of the opmachine, the path of movement of the' particles should be' practically unimpeded after the particles have been accelerated to high-blasting velocities. The slinger blades are therefore preferably provided with smooth continuous surfaces along which the particles may move with a minimum of friction in'response to the centrifugal force that is moving them outwardly along the slinger plates surfaces. d v' Each slinger blade or plate is supplied With the abradant material from its own basket acting as a valve, and, in order to reduce attrition to the plate to a minimum, each plate is mounted a short distance behind its basket so the trajectory'of the abradant particles, when they leave the basket, will approach thel slinger blade surface as an asymptote or substantial tangent to the trajectory of the particles. For that reason, it is also-therefore preferable to supply the abradant particles at a Zone of low speed, which is near the center of rotation; and then to feed the abradant particles from the central 10W-velocity zone ofthe rotor onto the slinger blades or plates, in a directioniwhich Will eliminate impact or batting of those particles, as they are fed t the platesfor acceleration and projection.` l

By means of thel construction illustrated, each basket provides a substantially measured amount of the abradant Vparticle'to each slinger lolade during each operation. The dimensions of the basket' may be varied according to the quantity or volume of each charge that is to be supplied to each blade.

Inl order` to control the point atwhch each basket will be operated to discharge a quantity of abradant' material to its blade, the electromagnet is mounted on a ring bracket 90 that is concentric with the rotor. The electro-magnet is adjustably disposed on the ring bracket 90 so it may beadjusted on the ring bracket, and then fixed in position to operate the valves successively as the respective armature plate 62 of each valve moves intol and by the effective magnetic zone of the electro-magnet.

The bracket 99 is supported for angular ad- J'ustment on a circular shoulder bracket 92 on an adjustable shaft 9| of the machine, so that by angularly adjusting the bracket 90 on the shoulder bracket 92, the magnet 5| may be disposed at any desired position around the circle, within the normal control angle that is necessary to control the point of feed of the abradant material to the slinger blades.

The circular shoulder 92 is shown, in Fig. l, as part ofthe shaft 9| that is co-axial with the dis-v tributor 3l). Y

`The circular shoulder is a ring-shaped element with a central opening `93, through which extends the supply conduit 9 4 of a feed hopperv for the abradant. The end of supply conduit 94 extends into the openv end of cylinder 3| ofthe 'distributor 3|),v and issuiriciently spaced from the ring-shaped shoulder 92 'to permit rotary adjustments of the shoulder 92 to be madewhile the conduit 94 is in position. f

The shoulder 92 and the shaft 9| are illustrated.

its "ed-'axial shaft' 9|, may .be made by'means of 7,J

l the electro-magnet 5|, the shaft 9| is angularly adjusted by its handle and then clamped in position, by a clamp 99 on a clamping plate |90 on the machine structure.

The manner in which the abradant material is fed to the slinger blades may now be considered, as controlled by the basket 38 and the control supply conduit 36 projecting down into the basket from the supply cylinder 3|. The leading edge 38a of the `basket is preferably made somewhat higherthan the trailing edge 38h. The lip of the trailing 3817 is preferably made somewhat lower` than the normal level line of the side edges of the basket 38, in order to permit some of the abradant material to slide off more easily from the trailing edge 38h of the v'basket 38. The control conduit 36 projects down into the basket somewhat below vthe top level of the side edges 38c of the basket 38. As the abradant material is centrifuged out of the cylinder 3| and through the control conduit 36 into the basket 38, that abradant material is held in the basket 38, and is i thus piled up in the bottom of the basket and is there held by centrifugal force, until the accumulating abradant' material reaches the mouth of the conduit 36 as a nozzle, and shuts off the mouth of the conduit 36, to prevent a further supply of the abradant material to the basket 38.

When some of the abradant of the basket is subsequently spilled out of the basket 38, thus leaving space for a further supply of abradant material to the basket 38, more abradant material moves through the transfer conduit 36 into the basket 38 until the supplyof abradant material in the basket 38 accumulates suiciently to again reach the mouth of the conduit 36 and shut off a further transfer.

The conduit 36 andthe material thus serve as a cut-olf control valve to supply abradant materialL tothe basket 38 only as-such abradant material is needed, and shut off such supply of material when the basket has an ample supply for the normal operation.

By tipping the basket clockwise around the pivot shaft 39, the trailing edge 3812 of the basket 38 is lowered, and the abradant material is shiftf ed to the trailing edge of the basket and is acted upon by a force that is a resultant of the normal centrifugal force and of a force component at an angle to the normal centrifugal force and in the direction of the plane of the surface 38d and tending to shift the abradant material over and off the trailing edge of the basket 38,

The material thus thrown out of the .basket sal is then thrown onto the associated slinger blade 29, by which it is then accelerated along the blade until it is thrown from the edge of the blade at predetermined zone on the path of travel of the outer edge of the blade, as controlled by the location" of the electro-magnet.

By means of the construction that is illustrated, each basketin sequence, is tipped through the small angle that is sucient to unload a portion of the abradant material that is already in the basket. As soon as the armature plate 62 passes out of the effective control range of the electromagnet 5|, centrifugal force again immediately forces the amature plate 62 radially outward, to its outermost position, and thereby restores the tipped basket .back to its normal loading position.

In order to help to guide the abradant material directly to the passages through the cylinder Wall, after the abradant material is supplied to the cylinder 3|, a guide cylinder |0| is fitted into the distributor cylinder 3| as a liner. The inner surface |02 of the guide liner |0| is slightly inclined or tapered in such direction as to move the abradant material inwardly from the mouth of the liner I towards the inner end of the distributor cylinder 3|, where the passages through the wall of the cylinder are disposed. In order further to aid and guide the distribution of the abradan-t material to those passages, the liner and guide cylinder |0| is provided with four semi-circular slots |03 that are disposed to be relatively concentric with the passages and with the conduits 36 through the wall of the distributor cylinder 3| These slots |03 act as pockets to receive a charge of the abradant material that is immediately directed and guided to, and supplied to, the associated conduit.

The guide lines cylinder |0| is also provided with an external radial fiange |04 by means of which the guide cylinder is secured to the distributor cylinder with threaded screws |65.

In order to provide an additional guiding influence andeffect upon the abradant material, when it reaches the inner end of the guide cylinder |0|, a guide plate |06 is provided and disposed adjacent the inner edge of the openings or passages through the distributor cylinder 3|.

The guide plate |06 is a circular plate of substantially saucer shape, with a rim |01 tapering toward the passages 32 to 3B, inclusive, so that any of the abradant material that may be forced inwardly against the plate |06 will tend to be centrifuged back out toward the regions occupied by the openings 32 to 35, in the distributor cylinder.

In order to keep the width dimensions of the blades 2ll as small as possible, and thereby permit the size of the other parts of the machine to be reduced to the minimum, the distributor cylinder 3l is shown supported on the end of the main shaft l2 in such manner as to bring the transfer passages, at the conduits, as close as possible to the main supporting back disc it upon which the transfer blades 20 are supported. .lhis permits the width of the blade to be kept to a minimum since the abradant material 1s transferred to the blades only a short distance away vfrom the front surface of tlie supporting disk le.

As shown in Figure 2, the distributor cylinder 3i 1s fitted over a reduced end portion of the main drive shaft l2, and is then further tightly clamped in position by two cooperating straps or clamps |l| and liz that are tightly secured to each other by suitable bolts Ils, only one or' which is shown on trie forward side of the drive shaft. The clamps |l| and l|2 are provided with annular flange sections H4 that fit into corresponding annular groove ||5 in the cylinder 3l.

The cylinder 3| may be press fitted over the end of tne shaft I2, or merely provided With a snug driving nt, that will be suflicient to prevent any looseness that would permit wabbling at the :free end of the distributor cylinder 3l under the inuence of the periodic magnetic forces, as each valve actuator is momentarily operated by the electro-magnet.

As shown in Figure 2, the guide plate |06 is secured to the end of the drive shaft I2 by a bolt and lock-washer ||8. The guide plate llll not only serves the function of guiding the material back and out toward the passages through the distributor cylinder 3|, but also protects the end surfaces of the drive shaft from the effect of the abradant material.

My invention is not limited to the specific details of construction that are illustrated since various modications might be made in those various details without departing from, spirit and scope of the invention as set forth in the appended claims.

I claim as my invention:

1. A blasting machine, comprising a rotor having a plurality of radial slinger blades, spaced to provide a central concentric opening; an abradant distributor in said central opening comprising a concentric cylinder fixed to rotate with the rotor and having peripherally spaced transfer openings adjacent the regions of the inner ends of the blades; a conduit extending through each transfer opening and a short distance beyond the outer plane of the cylinder; a bucket pivotally supported on the outside of the cylinder in position to surround and close the outer end of the conduit to control receipt of 'abradant material from the conduit; means for supplying abradant material to the cylinder; and means for tipping the bucket to discharge some of the abradant to the slinger blade.

2'. A blasting machine comprising a rotor having a plurality of radial slinger blades, and a central opening at the inner ends of the blades; and an abradant distributor for feeding the abradant material to the inner ends of the blades, said distributor comprising a concentric cylinder secured to the rotor, and having a transfer passage through t'ne cylinder wall near the inner end of each blade; a short conduit through each passage and projecting a short distance from the cylinder; a bucket pivotally supported on the cylinder and surrounding the end of each conduit with the end of each conduit between the top and the bottom levels of the bucket; means for tipping each bucket through a small angle to discharge some of the aoradant onto the associated blade; and means for supplying the abradant material to the cylinder.

3. A blasting machine comprising a rotor with radial slinger blades and a central opening at the inner ends of the blades; a concentric cylinder in the opening and i'lxed to the rotor, and having spaced openings through the cylinder Wall near the front sui-race ci' each blade; a conduit 1n each opening and extending a short distance from the cylinder; a bucket pivotally supported on the cylinder adjacent the end of the conduit to receive abradant transferred by the conduit, the bucket being supported so its normal center of gravity is in advance of its pivotal axis; means for tipping the bucket about its axis to discharge some abiadant onto the slinger blade, While keeping the center of gravity still in advance of its pivotal axis; means for restoring the bucket to neutral position; and means for supplying abradant material to the cylinder.

4. An abradant machine comprising a rotor having a plurality of slinger blades; and means for supplying a quantity of abradant material to the inner ends of the blades in sequence. comprising a concentric cylinder fixed to the rotor and provided with peripherally spaced openings through the cylinder Wall, and adjacent the .inner ends of the blades; means for supplying abradant material to the cylinder; and valve means for controlling the transfer of the abradant material from the cylinder to the blades through said spaced openings, said valvermeans including a conduit extending from` a spaced opening of the cylinder; a bucket at the end of the conduit with the conduit extending into the bucket to a .level below the top plane of the bucket, so the accumulation of the abradant in the bucket will terminatefurthertransfer of abradant through the conduit until therlevel of the abradant in the bucket is lowered by removal of some of the abradant from the bucket; means pivotally supporting the bucket; means normally holding lthe bucket in receiving position; and means for tipping the bucket at a selected position.

5. A blasting machine comprising a rotor having a plurality of radial slinger blades; means for supplying abradant material to the rotors; and means on the rotor for receiving the supply of abradant and feeding it to the blades, said means comprising a distributing cylinder concentric on the Vrotor and provided with radial openings through the cylinder wall respectively adjacent the inner` ends of the slinger blades; dispensing containers pivotally supported on the outside of the cylindenand respectively in position to receive the abradant passed through the radial openings in the cylinder wall, those containers being of such dimensions and so positioned between those openings and the radial slinger blades that said containers when tipped about their respective axes will spill some of the abradant material in a lagging slip stream onto the associated slinger blades with a minimum angle of approach to the surfaces of the slinger blades, to minimize wearing effect of the abradant on the slinger blades; and means for consecutively tipping the containers at a selected point in the,Y

path of travel kof the containers, to determine the point of feed of the abradant to the blades, and thereby their point of discharge.

6. In a blasting machine, a feed mechanism comprising a cylinder for receiving abradant material and having spaced outlets through the cylinder wall at a zone spaced from the inlet end of the cylinder; and a liner in the cylinder divergingly tapered from the inlet end to cause the abradant material to shift axially from the inlet to the outlets when the cylinder is rotated, the

liner having perforations at and concentric with.

the spaced outlets to constitute and serve as pockets for receiving and guiding the axially shifting material to the outlets.

7. A blasting machine comprising a rotor; a shaft therefor; a feed cylinder for the rotor, said cylinder having one end fitted over and secured to one end of the shaft to rotate therewith, and having peripherally spaced openings through its wall to serve as outlets for abradant material introduced into the cylinder through its open end; a tapered liner in thecylinder to guide the material from the inlet to the outlets of the cylinder; and a tapered end-plate on the end of the shaft for radially diverting to the outlets the abradant material that is axially moved from the inlet of the cylinder,

8. A blasting machine comprising a rotatable drive shaft; a cup-shaped container supported thereon and rotatable therewith, said container being adapted to receive a quantity of abradant material and to VVhold the material normally against discharge from the container during rotation; means for supplying abradant to the container; and means for moving the container from its normal position during rotation to a position at which some of the material is discharged over the rim of the container.

9. A blasting machine as in claim 8, in which a radial slinger blade is providedV to receive the discharged abradant from the container, and to propel the abradant ina selected direction.

" JULIUS E. FOSTER. 

